78447780 has 72 divisors (see below), whose sum is σ = 240464952. Its totient is φ = 20699136.

The previous prime is 78447767. The next prime is 78447797. The reversal of 78447780 is 8774487.

It can be written as a sum of positive squares in 4 ways, for example, as 29419776 + 49028004 = 5424^2 + 7002^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15214 + ... + 19706.

It is an arithmetic number, because the mean of its divisors is an integer number (3339791).

Almost surely, 2^78447780 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 78447780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (120232476).

78447780 is an abundant number, since it is smaller than the sum of its proper divisors (162017172).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

78447780 is a wasteful number, since it uses less digits than its factorization.

78447780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4605 (or 4600 counting only the distinct ones).

The product of its (nonzero) digits is 351232, while the sum is 45.

The square root of 78447780 is about 8857.0751379900. The cubic root of 78447780 is about 428.0819201507.

The spelling of 78447780 in words is "seventy-eight million, four hundred forty-seven thousand, seven hundred eighty".